The United States ambassador to the United Nations says the UN Security Council should take firmer action against the Angolan opposition movement, Unita.

Richard Holbrooke's words are the clearest sign yet that the US has distanced itself from the rebel movement which it backed during the Cold War.

Mr Holbrooke, who is currently on a tour in Africa, said in Luanda after talks with President Eduardo dos Santos that the sanctions regime against Unita should be strengthened and tightened.

He called for a special meeting of the Security Council to implement this.

Sanctions

Unita is currently barred from receiving fuel and arms supplies. The UN recently toughened measures designed to deny it profits from the diamond mines it controls.

President dos Santos: Human rights under scrutiny

Mr Holbrooke balanced his tough stance on Unita by raising human rights issues with Mr dos Santos, whose government has itself been accused of human rights violations including the recent arrest of a prominent journalist for writing an article critical of Angola's leaders.

This is nevertheless the firmest position which the US has yet taken against Unita - the movement which it supported against Angola's Soviet-backed government in the 1970s and 1980s.

US relations with the President dos Santos's government have warmed since the end of the Cold War and the withdrawal of Cuban troops from the country.

Herman Cohen, formerly secretary of state under President George Bush, told the BBC this week that only a few months ago Washington had been "hesitant" to give the Angolan Government its full support.

"They were still being even-handed and refusing to recognise that Unita and [leader Jonas] Savimbi were at fault in holding up the peace process," Mr Cohen said in an interview with Radio Four's The World Today.

Congo war concern

Mr Holbrooke later travelled to Namibia, where he said the civil war in the Democratic Republic of Congo was the most serious problem facing Southern Africa.

He was speaking after a meeting with President Sam Nujoma, who has sent troops to support Congolese President Laurent Kabila.

Mr Holbrooke said the ceasefire signed in Lusaka by government and rebels earlier this year had been eroded, and called for the urgent appointment of a peace mediator.

The US envoy also discussed the growing threat of HIV and AIDS in the region with Mr Nujoma.